Numbers 15 :38-40

Speak to the children of Yashra’al, and you shall say to them to make tzitzit on the corners of their garments throughout their generations, and to put a blue cord in the tzitzit of the corners. And it shall be to you for a tzitzit, and you shall see it, and shall remember all the commands of יהוה and shall do them, and not search after your own heart and your own eyes after which you went whoring,' 'so that you remember, and shall do all My commands, and be set-apart unto your Alohym.'